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What is the old fashioned grapefruit diet?

Losing weight is a goal for many people, and various diets and programs have been promoted over the years as solutions. One such diet that became popular in the 1930s and experienced a resurgence in the 1970s is the grapefruit diet, sometimes referred to as the “Hollywood diet.” This diet claims that grapefruit contains a fat-burning enzyme that can lead to rapid weight loss. Is there any truth to these claims? Let’s take a closer look at what the grapefruit diet is, its proposed effects, and whether it’s an effective approach for sustainable weight loss.

Overview of the Grapefruit Diet

The grapefruit diet is a short-term, restrictive fad diet that emphasizes consuming grapefruit with every meal. The diet first emerged in the 1930s and became popular again in the 1970s, touted as the eating plan favored by Hollywood stars. The grapefruit diet claims that grapefruit contains a fat-burning enzyme that enables rapid weight loss of up to 10 pounds in 12 days.

There are several variations of the grapefruit diet, but most follow a menu plan like this:

  • Breakfast: 1/2 grapefruit, two eggs, two strips of bacon
  • Lunch: 1/2 grapefruit, meat and vegetable
  • Dinner: 1/2 grapefruit, meat, vegetable, salad

In addition to grapefruit at every meal, the diet allows for drinking black coffee or tea and plenty of water. Meats, eggs, vegetables, and salad are permitted, while sugars, carbohydrates, and fatty foods are restricted.

Proposed Effects of the Grapefruit Diet

The grapefruit diet ascribes the potential for rapid weight loss to a fat-burning enzyme in grapefruit. However, there is no scientific evidence that grapefruit or its juices contain such an enzyme. Weight loss on this diet is simply due to its extreme calorie restriction, limiting intake to around 800-1000 calories per day. For comparison, the USDA recommends a daily intake of 2000 calories for women and 2500 for men to maintain body weight.

Some additional hypothesized effects of the grapefruit diet include:

  • Boosting metabolism – While grapefruit does contain good amounts of vitamin C and fiber, which can support metabolism, any increase would be marginal.
  • Suppressing appetite – The fiber and water content in grapefruit may help induce feelings of fullness.
  • Burning fat – No evidence supports targeted fat burning from grapefruit consumption.
  • Detoxification – Grapefruit provides antioxidants like vitamin C which can help eliminate free radicals. However, the body already detoxifies effectively when supported with a balanced diet.

Any benefits of grapefruit for weight loss are primarily due to its low calorie content and high water and fiber content providing satiety. The diet does not induce substantial, long-lasting changes to the metabolism or appetite regulation.

Does the Grapefruit Diet Work?

The grapefruit diet does typically lead to rapid weight loss of around 5-10 pounds in the short term. However, most of this initial weight loss is water weight and lean body mass rather than fat.

Here is a table examining the pros and cons of the grapefruit diet for weight loss:

Pros Cons
  • Fast initial weight loss
  • Emphasizes fruit and vegetables
  • Low in calories and fat
  • Simple to follow
  • Extremely restrictive and low in calories
  • Nutritionally unbalanced
  • Initial weight loss is mostly water and lean mass
  • Doesn’t teach sustainable habits
  • Weight regain is common

While the grapefruit diet may lead to fast initial weight loss, the severe calorie restriction causes the body to go into starvation mode. This slows the metabolism, causes fatigue and cravings, and leads to muscle breakdown. These effects make weight regain likely once normal eating is resumed.

Nutritional Concerns

The grapefruit diet is very low in calories, generally providing around 800-1000 calories per day. The USDA dietary guidelines recommend a minimum of 1200 calories daily for women and 1500 for men. Going below these thresholds over an extended period can result in nutrient deficiencies.

Here is a table comparing the nutritional recommendations for women to the typical intake on the grapefruit diet:

Nutrient RDA for Women Typical Grapefruit Diet
Calories 2000 800-1000
Protein 46g 30-40g
Fat 65g 10-15g
Carbohydrates 130g 50-100g
Fiber 25g 15-20g

As the table shows, the grapefruit diet provides inadequate intake of calories, protein, fat, carbs, and fiber compared to nutritional needs. These restrictions may lead to fatigue, hair loss, muscle breakdown, vitamin and mineral deficiencies, and even organ damage over time.

Side Effects

Due to its very low calorie intake and nutritional deficiencies, the grapefruit diet comes with many possible side effects:

  • Fatigue and weakness
  • Headaches
  • Dizziness and nausea
  • Muscle loss
  • Constipation or diarrhea
  • Nutrient deficiencies
  • Gallstones
  • Menstrual irregularities
  • Increased heart rate
  • Dehydration

These side effects stem from the diet providing inadequate fuel and nutrition for the body. Fatigue, headaches, and gastrointestinal issues commonly result as the body is deprived of calories and nutrients.

Long-Term Outlook

While the grapefruit diet may lead to weight loss in the short-term, it is extremely difficult to maintain over the long term due to nutritional inadequacy. Most dieters regain the lost weight quickly once they resume normal eating.

Yo-yo dieting in this way can slow metabolism, make weight loss harder, and increase the risk of disordered eating patterns. Going on this diet can also negatively affect psychological health due to the restriction and frequent feelings of hunger.

For successful long-term weight management, most experts recommend an eating pattern focusing on whole, minimally processed foods that provides a balance of lean proteins, healthy fats, complex carbs, and ample fruits and vegetables. Lifestyle changes like managing stress, getting quality sleep, and regular exercise are also key for effective and sustainable weight loss.

Who Should Avoid the Grapefruit Diet

Due to the extremely restrictive nature of the grapefruit diet, it is not suitable for many people and can even be dangerous. Those who should avoid this diet include:

  • Children and teens
  • Women who are pregnant or breastfeeding
  • People with diabetes or blood sugar regulation issues
  • Those taking certain medications that interact with grapefruit
  • People with a history of disordered eating
  • Those with a history of gallstones
  • Individuals with kidney problems or gout
  • People with heart disease, digestive disorders, or autoimmune conditions
  • Older adults

For those with medical conditions affected by weight loss, extremely low calories, specific nutrient restrictions, or grapefruit interactions, this diet should be avoided. Consulting with a doctor before making major dietary changes is always recommended.

Healthier Alternatives

While the grapefruit diet may lead to fast initial weight loss, it is an extreme and nutritionally unbalanced approach with high risks. Healthier and more sustainable alternatives for weight management include:

  • Balanced deficit diets – Reduce calories by 500-1000 daily from maintenance needs for a max loss of 1-2 lbs per week.
  • Intermittent fasting – Alternate fasting and eating days or restrict eating to set hours daily.
  • Low-carb diets – Limit carbohydrate intake to shift metabolism toward fat burning.
  • Mediterranean diet – Eat mostly plants, healthy fats, and lean proteins with some whole grains.
  • Flexitarian/vegetarian – Emphasize fruits, vegetables, legumes, whole grains, eggs, and dairy.
  • Volume eating – Focus on low calorie, nutrient-dense foods with high water and fiber content.

Any healthy weight loss diet should include all essential nutrients within your calorie needs, offer satiety between meals, and teach sustainable lifestyle habits.


In summary, the grapefruit diet involves eating grapefruit with every meal while severely restricting calories and food choices. While it may lead to significant short-term weight loss, it is nutritionally inadequate and the effects are temporary. Most of the initial weight loss comes from water and lean mass rather than fat.

The restrictive nature of the diet makes it difficult to adhere to long-term. It can slow the metabolism, cause undesirable side effects, and lead to weight regain once normal eating is resumed. For health and sustainable weight management, a balanced deficit diet with whole foods and lifestyle changes is a better approach.